The present invention relates a technology effective in applying to a device employed in a network where a working path and a recovery path are established for recovery from a failure in a GMPLS/MPLS (Generalized Multi-Protocol Label Switching/Multi-Protocol Label Switching) network, and to a method executed on this device.
In recent years, GMPLS and MPLS have been focused on for the purpose such as providing traffic engineering to an IP network and providing a VPN (Virtual Private Network) service. The GMPLS and the MPLS are technologies for actualization of forwarding data on the basis of label information. The GMPLS and the MPLS, for actualizing this type of data forwarding, requires constructing a label table in each relay node (LSR: Label Switched Router) having a GMPLS function and a MPLS function. Therefore, the GMPLS and the MPLS use signaling protocols (CR-LDP (Constraint-based Label Distribution Protocol)/RSVP-TE (ReSerVation Protocol with Traffic Extension), etc.), wherein the label table is organized, and the path is established (refer to Non-Patent document 1). Further, the GMPLS and the MPLS enable the user to check which LSR the in-use path extends through by executing the route trace. Namely, the user can check which LSR the designated path runs through by designating the path.
By the way, in the recent years, on the occasion of building up the network, a working path and a recovery path are often provided for improving a fault tolerance. The GMPLS and the MPLS are applicable also to the network thus provided with the working path and the recovery path. Further, an extension of the RSVP-TE signaling protocol such as GMPLS Based Segment Recovery for establishing the working path and the recovery path, is proposed (refer to Non-Patent document 2). The GMPLS Based Segment Recovery is a technology of segmenting the working path into a plurality of segments and automatically or manually establishing the recovery path that bypasses the individual segments.
[Non-Patent document 1]D. Awduche, Movaz, L. Berger, D. Gan, et al.,“RSVP-TE: Extensions to RSVP for LSP Tunnels”, Request for Comments: 3209
[Non-Patent document 2]Louis Berger, Igor Bryskin, Dimitri Papadimitriou, Adrian Farrel, “GMPLS Based Segment Recovery”, Internet Draft Updates: 3473
In the conventional GMPLS and the MPLS, the working path and the recovery path are recognized respectively as independent paths. Hence, a user is able to check, on the occasion of executing the route trace, which LSR the working path extends through by designating the working path and also to check which LSR the recovery path extends through by designating the recovery path. The user was, however, required to explicitly designate the path in order to execute the route trace and was unable to designate a path employed in the network at the present. Namely, the user could not check which LSR the now-in-use path extends through, unless the user would explicitly designate the now-in-use path after judging whether the now-in-use path is the working path or the recovery path. Therefore, problems arose in a case where the user could not judge whether the now-in-use path is the working system or not and a case that the judgment requires a considerable length of time.